Abstract
Abstract
We aimed to improve the detection sensitivity for liquid measurement by developing an ultrathin photoelectron transmission window (SiNx membrane) for liquid cells via X-ray photoelectron spectroscopy or X-ray photoelectron emission microscopy at an ultrahigh vacuum. The membrane using gas-cluster ion beams (GCIB) was thinned, and its burst pressure was compared with those of membranes thinned with atomic 400 eV Ar+ ions. The SiNx membranes thinned by GCIB had approximately 2.5 times higher burst pressure than Ar+ ions. In addition, the improved sensitivity of the characteristic X-ray from liquid water induced by low-energy electrons was investigated. With the use of the 4.5 nm-thick SiNx membrane etched by GCIB, the X-ray intensity became 1.6 times higher than those of the 11 nm-thick pristine membrane at the electron beam (EB) energy of 1.5 keV. This result showed a good agreement with Monte Carlo simulation results of the EB-induced X-ray emission from liquid water beneath the SiNx membrane.